Line an 8 by 4-inch loaf pan with waxed paper or aluminum foil. Brush the sides, but not the bottom lightly with butter and sprinkle the pumpkin seeds in the bottom.
Whisk the maple syrup, brown sugar, cream, corn syrup, pie spice, lemon juice, and salt together in a heavy-bottomed medium saucepan. Brush down the sides on the saucepan with water to remove every grain of sugar. Set the candy thermometer into the sugar. Cook the mixture over medium heat, without stirring, until the mixture reaches the firm ball stage, 248 degrees F, about 18 to 20 minutes.
Carefully stir in the pumpkin puree. Return to the heat and cook, stirring occasionally, until the caramel reaches the soft ball stage, 240 degrees F, about 15 minutes more. Remove from the heat and stir in butter and vanilla.
Pour the caramel over the pumpkin seeds in the prepared pan. Smooth to an even layer. Cool to room temperature.
When fully cooled peel from the waxed paper or foil and cut into 24 (1-inch) squares. Wrap individually in parchment or waxed paper and store in an airtight container for up to a week.